<div class="row">
    <div class="col-md-3">
        <select class="form-control" ng-model="province" ng-change="changeProvince(province)">
            <option value="">-- 请选择省份 --</option>
            <option value="{{item}}" ng-repeat="item in sProvinces">{{item}}</option>
        </select>
    </div>
    <div class="col-md-3" ng-if="province">
        <select class="form-control" ng-model="city" ng-change="changeCity(city)">
            <option value="">-- 请选择城市 --</option>
            <option value="{{c}}" ng-repeat="c in sCities">{{c}}</option>
        </select>
    </div>
    <div class="col-md-3" ng-if="city">
        <select class="form-control" ng-model="district" ng-change="changeDistrict(district)">
            <option value="">-- 请选择县区 --</option>
            <option value="{{item}}" ng-repeat="item in sDistrict">{{item}}</option>
        </select>
    </div>
    <div class="col-md-3" ng-if="district">
        <select class="form-control" ng-model="street" ng-change="changeStreet(street)">
            <option value="">-- 请选择乡镇/街道 --</option>
            <option value="{{item}}" ng-repeat="item in sStreet">{{item}}</option>
        </select>
    </div>
</div>